[英]Create IEnumerable<T> and add items to it
I have a given type
and a Comma Separated Values string
: 我有一个给定的
type
和一个逗号分隔值string
:
Type type = service.getType();
String csv = "1,2,3";
I need to convert the csv
string to an IEnumerable
of type
. 我需要将
csv
字符串转换为IEnumerable
type
。
I know that type
will be numeric, eg, int
, short
, long
, etc. 我知道
type
将是数字,例如int
, short
, long
等等。
I am able to spit the csv
and convert each one to given type
.. 我能够吐出
csv
并将每个转换为给定的type
..
String[] inputs = csv.Split(',');
TypeConverter converter = TypeDescriptor.GetConverter(modelType);
if (converter != null) {
foreach (String input in inputs) {
if (converter.CanConvertTo(type)) {
var number = converter.ConvertFromString(input);
// Add number to an IEnumerable of numbers
}
}
}
I am not able to create an IEnumerable
of type
and add numbers to it. 我无法创建
type
的IEnumerable
并向其添加数字。
How can I do this? 我怎样才能做到这一点?
You actually have the type at run-time, so you will need to use reflection to create an object of type List<T>
where T is the instance of class Type
which you are getting from service. 实际上,您在运行时就拥有该类型,因此您将需要使用反射来创建类型为
List<T>
的对象,其中T是从服务中获取的Type
类的实例。 The following code will create an instance of type List<T>
while T
is not type at compile time but instead it is resolved at run-time. 以下代码将创建
List<T>
类型的实例,而T
在编译时不是类型,而是在运行时解析。 Following is the code to create that: 以下是创建代码的代码:
var listTypeInstance = typeof(List<>);
var instanceList = listTypeInstance.MakeGenericType(type);
var numbers = (IList)Activator.CreateInstance(instanceList);
Now you can call the Add
method and add each number in it like: 现在,您可以调用
Add
方法,并在其中添加每个数字,如下所示:
var number = converter.ConvertFromString(input);
numbers.Add(number);
Adjusted in your code will look something like following: 在您的代码中进行了调整,如下所示:
var listTypeInstance = typeof(List<>);
var instanceList = listTypeInstance.MakeGenericType(type);
var numbers = (IList)Activator.CreateInstance(instanceList);
foreach (String input in inputs) {
if (converter.CanConvertTo(type)) {
var number = converter.ConvertFromString(input);
// Add number to an IEnumerable of numbers
numbers.Add(number);
}
Use dynamic
to skip the compile-time error. 使用
dynamic
跳过编译时错误。
var runtimeTypes = new List<Type>
{
typeof(int),
typeof(long)
};
foreach (var item in runtimeTypes)
{
var listType = typeof(List<>).MakeGenericType(item);
dynamic list = Activator.CreateInstance(listType);
list.Add(1); // Call Add() on dynamic works!
Console.WriteLine(list[0]);
}
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